The Great Northern Railway (GNR) Class O2 was a class of three-cylinder 2-8-0 steam locomotives designed by Nigel Gresley for freight work and built by the GNR from 1921. Further examples were built by the London and North Eastern Railway (LNER) from 1924.

The O2 was a three cylinder development of Gresley's O1 2-8-0 mineral locomotive, and was the first design to use his conjugated valve gear. In 1915, Gresley applied for patent rights for a conjugated valve gear using either rocking shafts or motion levers to control the valves on the central cylinder on a three cylinder locomotive.

The Great Northern Railway (GNR) Class O2 was a class of three-cylinder 2-8-0 steam locomotives designed by Nigel Gresley for freight work and built by the GNR from 1921. Further examples were built by the London and North Eastern Railway (LNER) from 1924.

The GNR O2 was development of the O1, which initially differed almost only in the number and arrangement of the cylinders. Instead of the previous two cylinders, three smaller ones were now used to improve power transmission and smooth running.

大型北部铁路（GNR） O2类是由奈杰尔·格雷斯利（Nigel Gresley）设计的三缸2-8-0蒸汽机车，由GNR从1921年开始建造。 Lner）从1924年开始。

Rebuilt to O2/1 with side-windowed cab. Retaining original GN-style cab. Number of locomotives logged in this class is 67. Number of locomotives with photos available in this class: 45.

The O2 locomotives were powerful three-cylinder heavy mineral engines with a 2-8-0 wheel arrangement. The first, a prototype, was completed in May 1918 by the Great Northern Railway (GNR). Production commenced in 1921 and the last appeared in …

Of the four LNER constituents that adopted the 0-8-0, only the GCR and GNR switched to 2-8-0s - significantly, both companies with long-distance coal traffic. Robinson launched his design for the GCR in 1911, while Gresley 's two-cylinder 1913 design on the GNR was followed by a three-cylinder version five years later.

Several O2s acquired B1-type boilers under Thompson’s grandiose plans of standardisation; and in the following listing their boiler numbers are prefixed with B1. In the interest of completeness it should be mentioned that two Robinson LNER Class …

No. 3841 was a class O2 2-8-0 steam locomotive that was built for the London, North Eastern Railway by Doncaster Works in 1942. BRDatabase